It is common practice to intermittently feed strip material by means of a reciprocating feed pawl which engages the strip during a feeding stroke thereby to push the strip in the direction of feeding. The feed pawl is often pivoted so that during the return stroke, the feed pawl can be dragged over the strip without pushing the strip in the reverse direction.
Feeding devices of the type briefly described above, whether they are of the bell crank type or of other types, can be troublesome if a high degree of precision is required in the strip feeding operation. For example, when the feed pawl is disengaged from the strip material, there may be a certain amount of "chattering" of the strip and/or the strip may be dragged in a reverse direction for a very short distance as a result of disengagement of the pawl. Furthermore, if the pawl remains in contact with the strip during the return stroke, the position of the strip on the feed path will be effected and the strip may vibrate or chatter as a result of the ratcheting effect of the pawl on the strip. If the operations being carried out on the strip material are relatively coarse, these effects are not troublesome, however, if precision stampings are being made, the slight movement of the strip brought about by the feeding mechanism causes substantial problems. For example, if the strip is being fed to a precision die, the slight movement of the strip in the die stations detracts from the dimensional precision of the finished parts. Also, if the strip material is in the form of precisely manufactured electrical terminals which are being fed to an assembly machine or to a crimping press, the misalignment of the strip in the assembly machine or in the crimping press will frequently give rise to inferior crimped connections.
The present invention is directed to the achievement of an improved strip feeding means of the bell crank type in which a high degree of precision in the feeding operation is obtained. Particularly, the invention is directed to the achievement of a bell crank type feeding mechanism in which the feed pawl is abruptly disengaged from the strip material being fed in a manner such that chattering or vibration in this strip at the end of the feeding stroke is virtually eliminated. The invention is also directed to the achievement of an improved feeding and shearing mechanism for a strip material and to an improved bell crank type mechanism which might be used in a variety of devices.